1. Field of the Invention
The present invention relates to a control of at least one of the recording and reproducing conditions in an apparatus for recording and reproducing information. The information recording and reproducing apparatus in the invention relates to an apparatus which performs either the recording or the reproduction of information or performs both the recording and reproduction of information.
2. Related Background Art
In the case of optically recording and reproducing information, there has been known a photo-electro-magnetic recording system in which a rare earth-transition metal amorphous system is used as a material of a recording medium, a laser beam is irradiated onto the recording medium upon recording, the surface of the recording medium is heated to a temperature near the Curie point, flux reversal is caused to form pits by applying an auxiliary magnetic field, and upon reproduction, information is reproduced by use of the well-known Kerr effect or Faraday effect.
This recording system presents the problem that when the record laser power and auxiliary bias magnetic field strength are constant, the sizes of pits which are recorded and the like are influenced due to differences of the static characteristics of the recording material, such as the coercive force Curie temperature, sensitivity, and the like of the recording medium. In the case of reproducing a signal in this state, a distortion occurs in the regenerated waveform, so that there is an occurrence of errors in the reproduced information.
To eliminate such an adverse influence, there is considered a system in which, in order to examine the characteristics of the disc, the recording and reproducing operations are repeated several times each time the disc is repeatedly used, thereby obtaining an optimum value. However, in the case of the optical disc of the DRAW (Direct Read After Write) type, the data which has once been recorded cannot be erased, so that there is a limitation in the automatic control of the record power or the like, since the record area and the number of recording times are limited.
On the other hand, in the case of an erasable magnetooptic disc and the like, if the automatic setting operation is performed each time the disc is mounted, it takes an additional time until the apparatus actually records and reproduces the data. Further, an additional apparatus for the automatic setting operation is needed, resulting in an increase in cost of the apparatus.
On the contrary, when using each disc without executing any adjustment, the ranges of the variations in recording sensitivity, coercive force, and the like of the disc must be set to small values. In turn, the productivity of the discs is also adversely influenced and the cost rises.